1. Field of the Invention
The present invention relates to horizontal tread support brackets or flanges attachable to sidewalls or stringers for carrying the weight of the treads and risers in a permanent stairway construction. More specifically, the present invention relates to a lazy tongs adjustable stair guide and support in which horizontal links having tread support flanges are uniformly spaced and interconnected by parallel, upright links.
2. Prior Art
It is conventional to frame a multistory building structure leaving a rough opening for a stairway between floors. The stairway then is laid out and constructed on the job after the vertical distance between the floors is known precisely. Notches can be cut in inclined stringers to support the ends of the stair treads and risers. The rise and run of each step must be substantially the same as the rise and run of each of the other steps, and within acceptable ranges as specified in the appropriate building code.
Even for multistory buildings having identical floor plans, the vertical distance between floors may vary depending upon the framing components used. For example, in conventional wood construction of residential buildings the vertical distance between floors will be approximately equal to the total of: the thickness of the bottom plate, the length of the studs, the thickness of the top plate or plates, the depth of the joists supporting the upper floor and the thickness of the subflooring material for the upper floor. The joists supporting the upper floor can be nominal "2.times.8", "2.times.10", or "2.times.12" lumber, and subflooring material of different thicknesses can be used depending on the spacing of the joists.
A problem with the conventional stairway construction is that it takes a substantial period to lay out and notch the stringers to assure that the rise and run of each step are uniform and within the range required by the building code.
Lyons U.S. Pat. No. 2,879,556, issued Mar. 31, 1959, discloses a stringer and template for stairway construction in the form of a strip of sheet metal that can be attached to unnotched, inclined stringers. The metal strip has tread and riser support flanges bent inward at right angles from the remaining, upright portion of the strip. The rise and run of each step is predetermined and cannot be adjusted to accommodate a range of vertical distances between floors.